/**
 * @Author Big_white
 * @Date 2021/11/11
 */
public class Screener {
    private static Screener instance=new Screener();
    public static Screener getInstance(){
        return instance;
    }
    public void up(){
        System.out.println("Screen up");
    }
    public void down(){
        System.out.println("Screen down");
    }

}
